Hydrogen generation device and fuel cell system equipped with same

ABSTRACT

A hydrogen generation apparatus according to the present invention includes: a hydrogen generator configured to generate a fuel gas through a reforming reaction by using a raw fuel; a combustor configured to heat the hydrogen generator; an on-off valve configured to open/block a gas passage through which the gas that is sent out from the hydrogen generator is supplied to the combustor; a combustion air supply device configured to supply combustion air to the combustor; an ignition device provided at the combustor; and a controller. In a case where flame extinction has occurred at the combustor during generation of a hydrogen-containing gas in a start-up process, the controller performs an ignition operation of the ignition device with the on-off valve kept opened.

TECHNICAL FIELD

The present invention relates to a hydrogen generation apparatus and afuel cell system including the hydrogen generation apparatus. Thepresent invention particularly relates to a hydrogen generationapparatus configured to generate a hydrogen-containing gas through areforming reaction by using steam and a raw fuel such as a natural gas,LPG, gasoline, naphtha, kerosene, or methanol, the raw fuel containingan organic compound of which constituent elements are carbon andhydrogen, and to a fuel cell system including the hydrogen generationapparatus.

BACKGROUND ART

In conventional hydrogen generation apparatuses for supplying a hydrogengas, a raw fuel containing an organic compound of which constituentelements are carbon and hydrogen is steam-reformed by a reformer thatincludes a reforming catalyst layer. Through this reforming reaction, ahydrogen-containing gas is generated (hereinafter, thehydrogen-containing gas may be simply referred to as a “hydrogen gas”,or alternatively, referred to as a “fuel gas”).

Conventional fuel cell systems use such a hydrogen gas to cause areaction between the hydrogen gas and an oxidizing gas such as air,thereby generating electric power and heat.

In a hydrogen generation apparatus, the reforming reaction, which is anendothermic reaction, progresses under a temperature of approximately600° C. to 700° C. Therefore, it is necessary to heat the reformingcatalyst layer in order to cause the reforming reaction to progress. Ingeneral, a combustion burner is used as means for heating the reformingcatalyst layer. A raw fuel containing an organic compound, or an offfuel gas unused in the fuel cell, is supplied to the combustion burneras a fuel for the combustion burner, and also, air or the like issupplied to the combustion burner as an oxidizing gas. As a result,combustion of such an air-fuel mixture occurs. In order to cause thecombustion of such an air-fuel mixture, an initial ignition of thecombustion burner is necessary. One general ignition method is togenerate electrical sparks by using an igniter (an ignition device) orthe like.

There are cases where the flame of the combustion burner goes out due tofluctuations and/or external disturbances in a supply system(hereinafter, such a situation where the flame goes out is referred toas “flame extinction”). If flame extinction occurs at the combustionburner, heat necessary for the reforming reaction cannot be supplied tothe reformer. This hinders the reformer from generating the hydrogengas. As a result, the generation of power and heat by the fuel cellcannot be continued.

In this respect, there is a proposed stop process as follows: if flameextinction occurs at the combustion burner during a warm-up mode of thereformer of the hydrogen generation apparatus, an on-off valve providedon a bypass pipe that bypasses the fuel cell is closed, the exit of thehydrogen generation apparatus is sealed off, and fuel supply to thecombustion burner is stopped; then, the combustion burner is purged byusing an oxidizing gas such as air; and thereafter, the combustionburner is ignited again (see, for example, Patent Literature 1). Itshould be noted that in the warm-up mode of the reformer, the steamreforming reaction in the reformer progresses, and thehydrogen-containing gas generated through the steam reforming reactionis supplied to the combustion burner via the bypass pipe.

-   PTL 1: Japanese Laid-Open Patent Application Publication No.    2008-91094

SUMMARY OF INVENTION Technical Problem

In such a conventional fuel cell system as described above, if flameextinction occurs at the combustion burner when the reforming reactionis progressing in the warm-up mode of the reformer, the bypass pipe isclosed and the hydrogen generation apparatus is sealed off.

Here, a rapid increase occurs in the amount of gas within the hydrogengeneration apparatus due to generation of steam from reforming watercontinuously fed to the hydrogen generation apparatus. This causes anincrease in the internal pressure of the hydrogen generation apparatuswhich is sealed off. Accordingly, pressure load is exerted on thecomponents of the hydrogen generation apparatus. It should be noted thateven if the reforming water is not continuously supplied into thehydrogen generation apparatus after the occurrence of the flameextinction of the combustor, it is expected that the same problem asabove occurs due to a rapid internal pressure increase that is caused byevaporation of the reforming water that remains within the hydrogengeneration apparatus.

The present invention has been made in view of the above problems. Thepresent invention is directed to a hydrogen generation apparatus that isconfigured to supply, while generating a hydrogen-containing gas in astart-up process through a reforming reaction using steam, thehydrogen-containing gas to a combustor to cause combustion, and anobject of the present invention is to provide a hydrogen generationapparatus that reduces, as compared to the conventional art, pressuredamage to its components at the time of igniting the combustor afterflame extinction has occurred at the combustor.

Solution to Problem

In order to solve the above problems, a hydrogen generation apparatusaccording to the present invention includes: a hydrogen generatorconfigured to generate a hydrogen-containing gas through a reformingreaction by using a raw fuel and steam; a combustor configured to heatthe hydrogen generator; an on-off valve configured to open/block a gaspassage through which the gas that is sent out from the hydrogengenerator is supplied to the combustor; an ignition device provided atthe combustor; and a controller. The combustor is configured to performcombustion during generation of the hydrogen-containing gas in astart-up process by using the gas that is supplied to the combustorthrough the gas passage. In a case where flame extinction has occurredat the combustor during the generation of the hydrogen-containing gas inthe start-up process, the controller performs an ignition operation ofthe ignition device with the on-off valve kept opened.

Further, the hydrogen generation apparatus according to the presentinvention includes: a combustion air supply device configured to supplycombustion air to the combustor; a raw fuel supply device configured tosupply the raw fuel to the hydrogen generator; and a water supply deviceconfigured to supply water to the hydrogen generator. In the case whereflame extinction has occurred at the combustor during the generation ofthe hydrogen-containing gas in the start-up process, the controllercauses the raw fuel supply device and the water supply device to supplythe raw fuel and the water to the hydrogen generator, and causes thecombustion air supply device to supply the combustion air to thecombustor, and performs the ignition operation of the ignition device,with the on-off valve kept opened.

Still further, in the hydrogen generation apparatus according to thepresent invention, if the combustor is not successfully ignited throughthe ignition operation, the controller performs a stop process of thehydrogen generation apparatus.

Still further, in the hydrogen generation apparatus according to thepresent invention, if the combustor is not successfully ignited throughthe ignition operation, the controller controls an operation amount ofthe combustion air supply device such that the operation amount becomesgreater than when the hydrogen-containing gas is being generated in thestart-up process.

Still further, the hydrogen generation apparatus according to thepresent invention includes: a first gas passage through which the gasthat is sent out from the hydrogen generator is guided into thecombustor in a manner to bypass a hydrogen utilization apparatus whichuses the hydrogen-containing gas; and a first on-off valve configured toopen/block the first gas passage. The combustor is configured tocombust, during the generation of the hydrogen-containing gas in thestart-up process, the gas that is supplied to the combustor through thefirst gas passage. In the case where flame extinction has occurred atthe combustor during the generation of the hydrogen-containing gas inthe start-up process, the controller performs the ignition operation ofthe ignition device with the first on-off valve kept opened.

Still further, the hydrogen generation apparatus according to thepresent invention includes: a heat exchanger configured to perform heatexchange between an exhaust gas discharged from the combustor and aheating medium; a heating medium passage through which the heatingmedium flows; a pump configured to cause the heating medium to flowthrough the heating medium passage; and a heat accumulator configured tostore heat that has been recovered by the heating medium. The controllercauses the pump to operate during the ignition operation of the ignitiondevice.

Still further, in the hydrogen generation apparatus according to thepresent invention, a period over which the ignition operation isperformed in said case is shorter than a period over which the ignitionoperation is performed at the start of the combustion of the combustorin the start-up process.

A fuel cell system according to the present invention includes: a secondgas passage through which a gas that is sent out from the hydrogengeneration apparatus according to the present invention is guided intothe combustor through a fuel cell; and a second on-off valve configuredto open/block the second gas passage. The combustor is configured tocombust, during the generation of the hydrogen-containing gas in thestart-up process, the gas that is supplied to the combustor through thesecond gas passage. In the case where flame extinction has occurred atthe combustor during the generation of the hydrogen-containing gas inthe start-up process, the controller performs the ignition operation ofthe ignition device with the second on-off valve kept opened.

Further, the fuel cell system according to the present inventionincludes the hydrogen generation apparatus according to the presentinvention and a fuel cell configured to generate power by using thehydrogen-containing gas that is supplied to the fuel cell from thehydrogen generation apparatus.

Advantageous Effects of Invention

According to the present invention, in a case where flame extinction hasoccurred at the combustor, the ignition operation is performed while agas passage through which a gas supplied from the hydrogen generator tothe combustor flows is kept opened. Accordingly, pressure damage to thehydrogen generation apparatus is reduced as compared to the conventionalart when the ignition operation is performed after the flame extinction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the configuration of ahydrogen generation apparatus according to Embodiment 1 of the presentinvention.

FIG. 2 is a block diagram showing an example of the configuration of ahydrogen generation apparatus according to Embodiment 2 of the presentinvention.

FIG. 3 is a block diagram showing an example of the configuration of afuel cell system according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram showing a variation of the hydrogen generationapparatus according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram showing a variation of the hydrogen generationapparatus according to Embodiment 2 of the present invention.

FIG. 6 is a block diagram showing a variation of the hydrogen generationapparatus according to Embodiment 2 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, various features of respective embodiments of the presentinvention are described below.

A hydrogen generation apparatus according to a first aspect includes: ahydrogen generator configured to generate a hydrogen-containing gasthrough a reforming reaction by using a raw fuel and steam; a combustorconfigured to heat the hydrogen generator; an on-off valve configured toopen/block a gas passage through which the gas that is sent out from thehydrogen generator is supplied to the combustor; an ignition deviceprovided at the combustor; and a controller. The combustor is configuredto perform combustion during generation of the hydrogen-containing gasin a start-up process by using the gas that is supplied to the combustorthrough the gas passage. In a case where flame extinction has occurredat the combustor during the generation of the hydrogen-containing gas inthe start-up process, the controller performs an ignition operation ofthe ignition device with the on-off valve kept opened.

With the above configuration, a countermeasure is taken against theflame extinction of the combustor. The countermeasure is to perform theignition operation of the ignition device in a state where the on-offvalve, which is configured to open/block the gas passage through whichthe gas sent out from the hydrogen generator is supplied to thecombustor, is kept opened.

In this manner, the hydrogen generator is maintained to be in a state ofbeing opened to the atmosphere through a flue gas passage even after theflame extinction has occurred at the combustor. Therefore, an increasein the internal pressure of the hydrogen generation apparatus that iscaused by a gas amount increase due to water evaporation is suppressed.Thus, pressure damage is reduced as compared to the conventional artwhen the ignition operation is performed after the flame extinction.

The “raw fuel” herein refers to a material that contains an organiccompound of which the constituent elements include at least carbon andhydrogen. A fuel gas is generated from the material through thereforming reaction. Examples of the “raw fuel” include hydrocarbons suchas methane, ethane, and propane, and alcohols such as methanol andethanol.

The “reforming reaction” includes both steam reforming reaction andautothermal reaction.

The “combustor” refers to, for example, a heating device such as acombustion burner configured to combust an air-fuel mixture. Asdescribed above, the “flame extinction at the combustor” refers to asituation where the flame of the “combustor” goes out.

The “ignition device” refers to, for example, an electrical ignitiondevice such as an igniter (spark plug). In this case, the “ignitionoperation of the ignition device” refers to an operation of electricallygenerating sparks by using the spark plug.

The “on-off valve” may be, for example, a solenoid valve of which thevalving element is opened/closed by electromagnetic force.

The “on-off valve configured to open/block a gas passage through whichthe gas that is sent out from the hydrogen generator is supplied to thecombustor” is realized as, for example, an on-off valve that is providedon a passage through which the gas that is sent out from the hydrogengenerator is guided into the combustor in a manner to bypass a hydrogenutilization apparatus (e.g., a fuel cell).

The wording “open/block a gas passage” (i.e., open and block a gaspassage) refers to opening/closing the internal gas-passing space of thegas passage. If the “on-off valve” is in an opened state, gas is allowedto flow through the gas passage. If the “on-off valve” is in a closedstate, gas is blocked from flowing through the gas passage.

The “controller” is configured as, for example, a microcomputer thatincludes a CPU and a memory. The “controller” may be either a singlecontroller or a plurality of controllers.

The “start-up process” includes a temperature increasing process ofincreasing the temperature of the hydrogen generator to a temperaturesuitable for the reforming reaction. The “start-up process” refers to aprocess that is performed before the hydrogen utilization apparatusstarts using the hydrogen-containing gas.

A hydrogen generation apparatus according to a second aspect may beconfigured such that the hydrogen generation apparatus according to thefirst aspect includes: a combustion air supply device configured tosupply combustion air to the combustor; a raw fuel supply deviceconfigured to supply the raw fuel to the hydrogen generator; and a watersupply device configured to supply water to the hydrogen generator. Inthe case where flame extinction has occurred at the combustor during thegeneration of the hydrogen-containing gas in the start-up process, thecontroller may cause the raw fuel supply device and the water supplydevice to supply the raw fuel and the water to the hydrogen generator,and cause the combustion air supply device to supply the combustion airto the combustor, and perform the ignition operation of the ignitiondevice, with the on-off valve kept opened.

According to this configuration, if the combustor is re-ignited throughthe ignition operation of the ignition device, the generation of thehydrogen-containing gas by the hydrogen generation apparatus can becontinued smoothly since the supply of the raw fuel to the hydrogengenerator by means of the raw fuel supply device and the supply of thewater to the hydrogen generator by means of the water supply device havebeen performed.

A hydrogen generation apparatus according to a third aspect may beconfigured such that, in the hydrogen generation apparatus according tothe first or second aspect, if the combustor is not successfully ignitedthrough the ignition operation of the ignition device, the controllerperforms a stop process of the hydrogen generation apparatus.

According to this configuration, during the generation of thehydrogen-containing gas in the start-up process, if an ignition is notproperly initiated through the ignition operation of the ignitiondevice, such a failed ignition is addressed properly.

It should be noted that a specific example of the “stop process of thehydrogen generation apparatus” will be described below.

A hydrogen generation apparatus according to a fourth aspect may beconfigured such that, in the hydrogen generation apparatus according toany one of the first to third aspects, if the combustor is notsuccessfully ignited through the ignition operation of the ignitiondevice, the controller controls an operation amount of the combustionair supply device such that the operation amount becomes greater thanwhen the hydrogen-containing gas is being generated in the start-upprocess.

According to this configuration, the amount of air sent to the combustorcan be increased, and therefore, the combustible gas within thecombustor can be diluted and discharged to the outside of the hydrogengeneration apparatus. If the combustor is not successfully ignited, theair from the combustion air supply device acts as a medium for coolingdown the hydrogen generation apparatus. Therefore, if the amount of theair is increased, the hydrogen generation apparatus can be cooled downsmoothly.

The “combustion air supply device” herein may be, for example, a blowersuch as a fan.

Among determining factors in an air amount fed to the combustor, the airamount representing the control amount of the “combustion air supplydevice”, a determining factor controllable by the “controller” (e.g.,the number of rotations of the fan) is herein referred to as the“operation amount of the combustion air supply device”. Accordingly, theair amount fed to the combustor is increased/decreased in accordancewith an increase/decrease in the “operation amount of the combustion airsupply device”.

A hydrogen generation apparatus according to a fifth aspect may beconfigured such that the hydrogen generation apparatus according to anyone of the first to fourth aspects includes: a first gas passage leadinginto the combustor in a manner to bypass a hydrogen utilizationapparatus which uses the hydrogen-containing gas; and a first on-offvalve configured to open/block the first gas passage. The combustor maybe configured to combust, during the generation of thehydrogen-containing gas in the start-up process, the gas that issupplied to the combustor through the first gas passage. In the casewhere flame extinction has occurred at the combustor during thegeneration of the hydrogen-containing gas in the start-up process, thecontroller performs the ignition operation of the ignition device withthe first on-off valve kept opened.

A hydrogen generation apparatus according to a sixth aspect may beconfigured such that the hydrogen generation apparatus according to thefirst or second aspect includes: a heat exchanger configured to performheat exchange between an exhaust gas discharged from the combustor and aheating medium; a heating medium passage through which the heatingmedium flows; a pump configured to cause the heating medium to flowthrough the heating medium passage; and a heat accumulator configured tostore heat that has been recovered by the heating medium.

The controller may cause the pump to operate during the ignitionoperation of the ignition device.

According to this configuration, even during the ignition operation ofthe ignition device that is performed when the combustor is notperforming combustion, the heat exchange between the exhaust gas and theheating medium is performed appropriately. As a result, heat recoveryfrom the exhaust gas is performed appropriately.

The “heat exchanger” may be configured as any device, so long as thedevice is intended to exchange heat between a high-temperature fluid(heating fluid) and a low-temperature fluid (heat receiving fluid).

Considering the thermal efficiency of the fuel cell system, it ispreferred to recover heat from the exhaust gas through the heatexchange. The recovered heat may be used for hot water supply, floorheating, etc. In this case, piping that is connected to the heataccumulator (e.g., the heat accumulator is a hot water tank for hotwater supply or a passage that forms a floor heating system) may be usedas the “heating medium passage”

Preferably, the “heating medium” is a liquid. For example, water in aliquid form or an antifreezing fluid may be used as the “heatingmedium”.

The “pump” may be configured in any form, so long as the pump isconfigured to cause the heating medium to flow through the heatingmedium passage.

The “exhaust gas” refers to a gas discharged from the combustor.Examples of the “exhaust gas” include: a flue gas that is generated dueto combustion of an air-fuel mixture of a combustion fuel and combustionair; and the combustion air when the combustion of the combustor isstopped.

A hydrogen generation apparatus according to a seventh aspect may beconfigured such that, in the hydrogen generation apparatus according tothe first or second aspect, a period over which the ignition operationof the ignition device is performed in said case is shorter than aperiod over which the ignition operation of the ignition device isperformed at the start of the combustion of the combustor in thestart-up process.

When flame extinction has occurred at the combustor during thegeneration of the hydrogen-containing gas in the start-up process, theamount of combustible gas present within the combustor at the time isgreater than when the ignition operation is performed at the start ofthe combustion in the start-up process. Therefore, if the period of theignition operation that is performed in the case where flame extinctionhas occurred at the combustor during the generation of thehydrogen-containing gas in the start-up process, is prolonged, thenthere is a possibility that the combustible gas is discharged to theoutside of the hydrogen generation apparatus through the flue gaspassage. Here, the possibility that the combustible gas is discharged tothe outside of the hydrogen generation apparatus can be reduced bysetting the period of the ignition operation that is performed in thecase where flame extinction has occurred during the generation of thehydrogen-containing gas in the start-up process to be shorter than theperiod of the ignition operation that is performed at the beginning ofthe start-up process. The “period of the ignition operation” hereinrefers to, in the case of the ignition operation of, for example, anigniter, a period over which the igniter continuously generates sparksto cause an ignition. The “period of the ignition operation” herein doesnot refer to an overall ignition period including a retry ignitionoperation that is performed after pre-purge (purging by air) of thecombustor.

A fuel cell system according to a first aspect may include the hydrogengeneration apparatus according to the first to seventh aspects and afuel cell configured to generate power by using the hydrogen-containinggas that is supplied to the fuel cell from the hydrogen generationapparatus.

A fuel cell system according to a second aspect, which includes thehydrogen generation apparatus according to the first to fourth aspects,may include: a second gas passage leading into the combustor through afuel cell which uses the hydrogen-containing gas; and a second on-offvalve configured to open/block the second gas passage. The combustor maybe configured to combust, during the generation of thehydrogen-containing gas in the start-up process, the gas that issupplied to the combustor through the second gas passage. In the casewhere flame extinction has occurred at the combustor during thegeneration of the hydrogen-containing gas in the start-up process, thecontroller performs the ignition operation of the ignition device withthe second on-off valve kept opened.

Embodiment 1

Hereinafter, specific configuration examples and operational examples ofa hydrogen generation apparatus according to Embodiment 1 of the presentinvention will be described with reference to the accompanying drawings.

It should be noted that the specific description given below merelyindicates examples of the hydrogen generation apparatus's features thatare recited above at the beginning of Description of Embodiments. Forexample, in the description of specific examples below, the same termsas those used above to specify respective components of the hydrogengeneration apparatus may be used with corresponding reference signsadded thereto. In such a case, in the description below, each devicespecified by a term with a reference sign added thereto is merely anexample of a component that is specified by the same term in the abovedescription of the hydrogen generation apparatus.

Accordingly, the above-described features of the hydrogen generationapparatus are not limited by the specific description given below.

[Example of Configuration of Hydrogen Generation Apparatus]

FIG. 1 is a block diagram showing an example of the configuration of thehydrogen generation apparatus according to Embodiment 1 of the presentinvention.

As shown in FIG. 1, a hydrogen generation apparatus 100 includes ahydrogen generator 1 configured to generate a hydrogen-containing gasthrough a reforming reaction by using a raw fuel and steam. The hydrogengeneration apparatus 100 also includes a raw fuel supply device 20configured to supply a raw fuel to the hydrogen generator 1, and a watersupply device 12 configured to supply reforming water necessary for thereforming reaction in the hydrogen generator 1.

When the raw fuel and water are supplied to the hydrogen generator 1,the hydrogen generator 1 causes a reforming reaction between the rawfuel and water at a reforming catalyst layer (not shown). As a result, ahydrogen-containing gas is generated in the hydrogen generator 1.Although a reformer (not shown) that includes the reforming catalystlayer is provided within the hydrogen generator 1, such an internalconfiguration of the hydrogen generator 1 is publicly known. Therefore,a detailed description of the internal configuration is omitted below,and the internal configuration is not shown in the drawings. It shouldbe noted that, depending on the configuration of the hydrogen generator,the hydrogen generator may include, in addition to the above-describedreformer, a shift converter or a carbon monoxide remover together withthe reformer for the purpose of reducing carbon monoxide in thehydrogen-containing gas, the shift converter being configured to reducecarbon monoxide through a shift reaction and the carbon monoxide removerbeing configured to reduce carbon monoxide through an oxidationreaction. The hydrogen generation apparatus 100 according to the presentembodiment is configured such that the hydrogen-containing gas isgenerated through a steam reforming reaction. However, as analternative, the hydrogen-containing gas may be generated through anautothermal reaction. In such a case, the hydrogen generation apparatus100 includes an air supply device (not shown) configured to supply airto the hydrogen generator 1.

The raw fuel supply device 20 is connected to, for example, a raw fuelsource (e.g., a city gas infrastructure or a propane gas canister). Abooster pump, a flow rate adjusting valve, or the like may be used asthe raw fuel supply device 20. In such a case, the raw fuel supplydevice 20 supplies the hydrogen generator 1 with a city gas which is anexample of the raw fuel and which contains methane gas as a maincomponent.

The water supply device 12 is connected to, for example, a water source(e.g., a water infrastructure or a water tank). A pump, a flow rateadjusting valve, or the like is used as the water supply device 12.

The reforming reaction (which is an endothermic reaction) at thereforming catalyst layer progresses under a high temperature ofapproximately 600° C. to 700° C. Therefore, a combustor 2, which isconfigured to heat the hydrogen generator 1 from the outside to increasethe temperature of the reforming catalyst layer, is necessary in orderto cause the reforming reaction in the hydrogen generator 1 to progress.

Accordingly, as shown in FIG. 1, the hydrogen generation apparatus 100includes: the combustor 2 configured to heat the hydrogen generator 1; acombustion air supply device 4 configured to supply the combustor 2 withair for use in combustion (hereinafter, simply referred to as“combustion air”); and an ignition device 5 provided at the combustor 2.

A fan configured to send to the combustor 2 an atmosphere (air)containing oxygen necessary for the combustion may be used as thecombustion air supply device 4, for example. However, the combustion airsupply device 4 need not be a fan. Any other device may be used as thecombustion air supply device 4, so long as the device is configured tosupply air. For example, a pump may be used as the combustion air supplydevice 4.

It should be noted that the supply of a fuel for use in the combustion(hereinafter, simply referred to as a combustion fuel) to the combustor2 will be described in detail below.

When the combustion fuel and the combustion air are supplied to thecombustor 2, combustion of an air-fuel mixture of the combustion fueland the combustion air occurs within the combustor 2.

The ignition device 5 is used as an ignition source for causing theair-fuel mixture of the combustion fuel and the combustion air to beignited in the combustor 2. As one example, an igniter (a spark plug)that electrically generates sparks may be used as the ignition device 5.Further, as shown in FIG. 1, the combustor 2 is provided with a flamedetector 21 configured to detect presence or absence of a flame. As oneexample, a frame rod may be used as the flame detector 21.

As shown in FIG. 1, the hydrogen generation apparatus 100 includes ahydrogen utilization apparatus 7 configured to utilize thehydrogen-containing gas generated by the hydrogen generator 1. Examplesof the hydrogen utilization apparatus include a hydrogen storage tankand a fuel cell. In the present embodiment, a hydrogen storage tank isused as the hydrogen utilization apparatus.

As shown in FIG. 1, the hydrogen generation apparatus 100 includes anon-off valve configured to open/block (open and block) a gas passagethrough which the gas that is sent out from the hydrogen generator 1 issupplied to the combustor 2. Accordingly, the internal gas-passing spaceof the gas passage can be opened and closed by using the on-off valve.

The gas passage is realized as a first gas passage 8 through which acombustible gas (e.g., a fuel gas) that is sent out from the hydrogengenerator 1 is guided into the combustor 2 in a manner to bypass thehydrogen utilization apparatus 7. The on-off valve is realized as afirst on-off valve 8A configured to open/block the first gas passage 8.

Fluid piping that forms a fluid passage may be used as the first gaspassage 8, for example. A solenoid valve configured to open/close theinternal space of the fluid piping may be used as the first on-off valve8A, for example. It should be noted that a third on-off valve 9B (e.g.,a solenoid valve) is provided on fluid piping that connects the hydrogengenerator 1 and the hydrogen utilization apparatus 7.

As shown in FIG. 1, the hydrogen generation apparatus 100 includes acontroller 30.

The controller 30 includes, for example, a CPU and a memory. Thecontroller 30 controls operations of its various control target devicesthat are included in the hydrogen generation apparatus 100, based onsignals from various detectors of the hydrogen generation apparatus 100.

In the hydrogen generation apparatus 100 according to the presentembodiment, if for example the controller 30 detects the flameextinction of the combustor 2 by means of the flame detector 21, thecontroller 30 performs control to maintain a “state where the on-offvalve configured to open/block the gas passage through which the gassent out from the hydrogen generator 1 is supplied to the combustor 5 iskept opened”. In such a state, the ignition operation of the ignitiondevice 5 is performed. If the combustor 2 is not successfully ignitedthrough the ignition operation of the ignition device 5, the controller30 performs a stop process of the hydrogen generation apparatus 100. Inaddition, if the combustor 2 is not successfully ignited through theignition operation of the ignition device 5, the controller 30 controlsthe operation amount of the combustion air supply device 4 such that theoperation amount becomes greater than when the hydrogen generationapparatus is generating the hydrogen-containing gas in a start-upprocess.

It should be noted that these controls performed by the controller 30will be described below in detail.

[Example of Normal Operations of Hydrogen Generation Apparatus]

Hereinafter, an example of normal operations of the hydrogen generationapparatus 100 according to Embodiment 1 of the present invention isdescribed. It should be noted that operations described below areperformed as a result of the controller 30 controlling respectivecomponents of the hydrogen generation apparatus 100.

The normal operations of the hydrogen generation apparatus 100 areroughly categorized into the following steps: a start-up process, ahydrogen supply operation, a stop process, and a standby state. Sincethese steps are publicly known, they are described below briefly.

(Start-Up Process)

The start-up process of the hydrogen generation apparatus 100 isperformed when the hydrogen generation apparatus 100 is in a pre-startupstate (e.g., a standby state described below). The start-up process is aprocess of starting and thereby causing the hydrogen generationapparatus 100 in the pre-startup state to become ready to stablygenerate a hydrogen-containing gas containing hydrogen at a highconcentration. In the start-up process, a temperature increasing processof increasing the temperature of the hydrogen generator 1 to a suitabletemperature is performed.

In the temperature increasing process, the combustion fuel and thecombustion air are supplied to the combustor 2, and the air-fuel mixtureof the combustion fuel and the combustion air is combusted in thecombustor 2 by means of the ignition device 5. The combustion air issupplied to the combustor 2 by means of the combustion air supply device4. Moreover, in the start-up process, the combustion fuel is supplied tothe combustor 2 in a manner described below. A raw fuel gas sent outfrom the hydrogen generator 1, which is supplied to the combustor 2through the first gas passage 8, is ignited and thereby the combustionstarts, and thereafter, a combustible gas continuously sent out from thehydrogen generator 1 is used as the combustion fuel for the combustor 2.

In this manner, the hydrogen generator 1 is heated up. When thetemperature of the reforming catalyst layer of the hydrogen generator 1is increased to reach a temperature necessary for the reformingreaction, the water supply device 12 starts supplying water to thehydrogen generator 1. Accordingly, the hydrogen-containing gas isgenerated from the raw fuel and steam through the reforming reaction.When the temperature of the reforming catalyst layer of the hydrogengenerator 1 has been sufficiently increased so that a high-qualityhydrogen-containing gas (hereinafter, a hydrogen gas), in which ahydrogen concentration is high, can be stably generated, the operationadvances to the hydrogen supply step of the hydrogen generationapparatus 100, which is described below.

(Hydrogen Supply Step)

The hydrogen supply step of the hydrogen generation apparatus 100 is astep of supplying the hydrogen gas, which is generated by the hydrogengenerator 1, to the hydrogen utilization apparatus 7.

In the hydrogen supply step, the high-quality hydrogen gas is suppliedto the hydrogen utilization apparatus 7, and the hydrogen utilizationapparatus 7 uses the hydrogen gas. In the hydrogen supply step, thethird on-off valve 9B is opened for the purpose of supplying thehydrogen gas to the hydrogen utilization apparatus 7. Here, the firston-off valve 8A is also opened similar to the start-up process.Accordingly, the hydrogen gas that is sent out from the hydrogengenerator 1 and that flows through the first gas passage 8 is partiallysupplied to the combustor 2 as a combustion fuel.

(Stop Process)

The stop process of the hydrogen generation apparatus 100 is a processof stopping the hydrogen generation apparatus 100 from generating thehydrogen gas.

The stop process described below is performed, for example, in thefollowing case: a case where the hydrogen demand of the hydrogenutilization apparatus has decreased; or a case where a user hasinputted, via an operation device which is not shown, an instruction tostop the operation of the hydrogen generation apparatus 100. It shouldbe noted that the case where the hydrogen demand of the hydrogenutilization apparatus has decreased refers to a case where, assumingthat the hydrogen utilization apparatus is a hydrogen storage tank, thehydrogen storage tank contains a sufficient amount of hydrogen, or acase where, assuming that the hydrogen utilization apparatus is a fuelcell, the power demand of an electrical load has decreased to be lessthan or equal to a predetermined power threshold, so that the electricalload does not require power supply from the fuel cell.

In the stop process, the supply of the raw fuel and water to thehydrogen generator 1 is stopped. Also, the supply of the hydrogen gas asa combustion fuel to the combustor 2 is stopped. As a result, thecombustion of the combustor 2 is stopped. In this case, however, it isusual to continue for a while the supply of the combustion air from thecombustion air supply device 4. In this manner, the combustible gas thatremains within the combustor 2 can be purged.

(Standby State)

The standby state of the hydrogen generation apparatus 100 is a state ofstanding by after the stop process is completed. In the standby state,the operation stands by in preparation for the next start-up until aninstruction to perform the next start-up is given.

In the standby state, when a request for the start-up of the hydrogengeneration apparatus 100 occurs, the controller 30 outputs aninstruction to start up the hydrogen generation apparatus 100, therebystarting the start-up process. It should be noted that the occurrence ofthe start-up request refers to an increase in the hydrogen demand of thehydrogen utilization apparatus, or an input of an operation startinstruction by an operator using an operation device (not shown).Moreover, the increase in the hydrogen demand of the hydrogenutilization apparatus refers to the following case: a case where,assuming that the hydrogen utilization apparatus is a hydrogen storagetank, the amount of hydrogen contained in the tank has decreased to beless than or equal to a predetermined threshold, so that the tank needsto be supplied with hydrogen; or a case where, assuming that thehydrogen utilization apparatus is a fuel cell, the power demand of anelectrical load has increased to be greater than or equal to apredetermined power threshold, so that the electrical load requirespower supply from the fuel cell.

[Example of Operations Performed When Flame Extinction of Combustor HasOccurred during Hydrogen-Containing Gas Generation in Start-Up Processof Hydrogen Generation Apparatus 100]

In a case where a combustion burner is used as the combustor 2, there isa possibility that the flame of the combustor 2 goes out, causing flameextinction. One of the conceivable causes of the flame extinction of thecombustor 2 is a transient disturbance in balance between a supplyamount of the combustion fuel and a supply amount of the combustion air.In particular, when the hydrogen-containing gas is being generated, arapid gas volume expansion due to evaporation of water supplied to thehydrogen generator causes a variation in the amount of combustible gasflowing into the combustor 2. This increases the possibility of flameextinction.

When the hydrogen generation apparatus 100 is generating thehydrogen-containing gas, if flame extinction occurs at the combustor 2and the hydrogen generation apparatus 100 stops operating, accordingly,then the energy used to increase the temperature of the hydrogengenerator 1 is wasted. The flame extinction of the combustor 2 is oftencaused by, for example, a transient disturbance in a gas amount suppliedto the combustor 2. Therefore, if the supply of the raw fuel, water, andthe combustion air is continued in the same manner as before theoccurrence of the flame extinction, it is expected that the gaseousair-fuel mixture within the combustor 2 remains in an air-fuel ratiothat allows the air-fuel mixture to be combusted in the combustor 2.Therefore, usually, the ignition operation is performed, attempting toresume the combustion operation of the combustor 2.

In the hydrogen generation apparatus 100 according to the presentembodiment, if flame extinction occurs at the combustor 2 when thehydrogen generation apparatus 100 is generating the hydrogen-containinggas in the start-up process, then the ignition operation of the ignitiondevice 5 is performed with the first on-off valve 8A kept opened,instead of the above-described conventional stop process. Specifically,the ignition operation of the ignition device 5 is performed in such amanner as described in an example below. It should be noted thatoperations described below are performed as a result of the controller30 controlling respective components of the hydrogen generationapparatus 100.

In a case where flame extinction has occurred at the combustor 2 duringthe hydrogen-containing gas generation by the hydrogen generationapparatus 100 in the start-up process, the flame extinction is detectedbased on an output signal from the flame detector 21. Thereafter, thesupply of the raw fuel to the hydrogen generator 1 by means of the rawfuel supply device 20, the supply of water to the hydrogen generator 1by means of the water supply device 12, and the supply of the combustionair from the combustion air supply device 4 are continued, with thefirst on-off valve 8A kept opened. Also, the controller 30 controls theignition device 5 to operate to perform an ignition operation.

As described above, the hydrogen generation apparatus 100 of the presentembodiment performs an ignition operation with the first on-off valve 8Akept opened. This makes it possible to re-ignite the combustor 2, withreduced pressure damage to the hydrogen generation apparatus 100 ascompared to the conventional art.

Further, the period of the ignition operation of the ignition device 5that is performed in the above case is set to be shorter than the periodof the ignition operation of the ignition device 5 that is performed tostart the combustion of the combustor 2 for the purpose of starting thetemperature increasing step of the hydrogen generator 1 in the start-upprocess of the hydrogen generation apparatus 100. The reason for this isdescribed below.

The “period of the ignition operation” herein refers to, in the case ofthe ignition operation of, for example, an igniter, a period over whichthe igniter continuously generates sparks. The “period of the ignitionoperation” herein does not refer to an overall ignition period includinga retry ignition operation that is performed after pre-purge (purging byair) of the combustor 2.

In the start-up process of the hydrogen generation apparatus 100, theconcentration of combustible components in the air-fuel mixture of thecombustion air and the combustion fuel can be gradually increased from anon-combustible concentration to a combustible concentration while theignition operation of the ignition device 5 is being performed.Accordingly, even if the period of the ignition operation is set to berelatively long, it does not cause a problem.

In contrast, in a case where flame extinction has occurred at thecombustor 2 during the generation of the hydrogen-containing gas in thestart-up process, it can be assumed that the concentration ofcombustible components in the air-fuel mixture of the combustion air andthe combustion fuel within the combustor 2 is already a combustibleconcentration. Accordingly, if the period of the ignition operation thatis performed in this case is set to be relatively long, the air-fuelmixture is forced to the downstream side of the combustor 2 due to thegas that is supplied to the combustor 2 during the period of theignition operation. This may result in the air-fuel mixture beingdischarged to the outside of the hydrogen generation apparatus 100through an exhaust outlet 300 which is disposed at the downstream end ofa flue gas passage.

In view of the above, in order to suppress extended diffusion ofcombustible gas (i.e., the air-fuel mixture in which the concentrationof combustible components is a combustible concentration), it ispreferred in this case that the period of the ignition operation of theignition device 5 is set to be shorter than the period of the ignitionoperation of the ignition device 5 that is performed to start thetemperature increasing step in the start-up process of the hydrogengeneration apparatus 100. In addition, in order to suppress extendeddiffusion of the combustible gas, it is preferred in this case that theignition operation of the ignition device 5 is performed only once.

According to the above settings, the discharge of the combustible gas tothe outside of the hydrogen generation apparatus 100 is suppressed.

Moreover, the period of the ignition operation of the ignition device 5is set to a predetermined short period of time (a few seconds; forexample, “six seconds”). Therefore, the generation of thehydrogen-containing gas by the hydrogen generation apparatus 100 can becontinued even during the period of the ignition operation. Accordingly,if the combustor 2 is re-ignited by the ignition operation of theignition device 5, the combustion of the combustor 2 can be continuedwithout interrupting the generation of the hydrogen-containing gas bythe hydrogen generation apparatus 100. It should be noted that whetherthe combustor 2 has been ignited is determined based on an output signalfrom the flame detector 21.

In the hydrogen generation apparatus 100 according to the presentembodiment, there may be a case where the combustor 2 is not ignited bythe ignition operation of the ignition device 5 even if the ignitionoperation of the ignition device 5 is performed for a period longer thanthe predetermined “six seconds”. In such a case, flame extinctionabnormal stop process of the hydrogen generation apparatus 100, whichwill be described below, is performed by the controller 30.

It should be noted that whether an abnormal ignition, in which thecombustor 2 is not ignited, has occurred is determined based on anoutput signal from the flame detector 21. The predetermined period “sixseconds” is merely an example. The period of the ignition operation maybe set to any appropriate period depending on, for example, deviceconfigurations and a gas flow rate, so long as the set period does notcause the air-fuel mixture containing the combustible gas to bedischarged from the exhaust outlet 300 during the period of the ignitionoperation.

Immediately after the flame extinction abnormal stop of the hydrogengeneration apparatus 100 is performed, the combustible gas still existswithin the combustor 2. Therefore, the combustion air supply device 4 isoperated, and thereby the combustible gas is diluted with air anddischarged to the outside of the hydrogen generation apparatus 100. Inthis case, in the hydrogen generation apparatus 100 according to thepresent embodiment, the operation amount of the combustion air supplydevice 4 may be made greater than the operation amount of the combustionair supply device 4 during the hydrogen-containing gas generation in thestart-up process of the hydrogen generation apparatus 100. In thismanner, the combustible gas that remains within the combustor 2 istreated appropriately.

In the flame extinction abnormal stop process of the hydrogen generationapparatus 100, the supply of the raw fuel and water to the hydrogengenerator 1 is stopped. However, the raw fuel, steam, and water stillremain within the hydrogen generator 1. Moreover, immediately after thehydrogen generation apparatus 100 has stopped, heat that is sufficientfor the remaining water to evaporate and for generating the hydrogen gasthrough the reforming reaction between the remaining raw fuel and steamis still stored in the hydrogen generator 1.

Therefore, similar to the conventional art, if the first gas passage 8which bypasses the hydrogen utilization apparatus 7 (fuel cell) issealed off, then there occurs a gas amount increase (an increase in thenumber of moles of gas) due to the hydrogen gas generation and waterevaporation, resulting in an increase in the internal pressure of thehydrogen generator 1. This may cause structural damage to the hydrogengenerator 1.

In view of the above, in the hydrogen generation apparatus 100 accordingto the present embodiment, after the supply of the raw fuel and water tothe hydrogen generator 1 is stopped, the first on-off valve 8A is keptopened.

Accordingly, the combustion air is supplied from the combustion airsupply device 4 to the combustor 2 in a state where the first gaspassage 8 is opened. As a result, an increase in the internal pressureof the hydrogen generator 1 can be suppressed even while the inside ofthe combustor 2 is purged with the combustion air (hereinafter, this isreferred to as an “excessive pressure increase suppressing operation”).

If the excessive pressure increase suppressing operation is performed,there is a possibility that the combustible gas is discharged to theoutside of the hydrogen generation apparatus 100 through the exhaustoutlet 300 which is disposed at the downstream end of the flue gaspassage 10. In the present embodiment, however, the combustion airsupply device 4 is operated as described above, and thereby thecombustible gas is diluted and the combustible gas concentration isreduced. Then, the diluted gas is discharged to the outside of thehydrogen generation apparatus 100. In this case, the amount of airsupplied from the combustion air supply device 4 (specifically, theoperation amount of the combustion air supply device 4) may be set inconsideration of the amount of combustible components in the combustiblegas discharged through the excessive pressure increase suppressingoperation, aiming at preventing the combustible gas in which theconcentration of combustible components is a combustible concentrationfrom being discharged to the outside of the hydrogen generationapparatus 100.

As described above, the hydrogen generation apparatus 100 according tothe present embodiment includes: the hydrogen generator 1 configured togenerate a fuel gas through a reforming reaction by using a raw fuel;the combustor 2 configured to heat the hydrogen generator 1; an on-offvalve configured to open/block a gas passage through which the gas thatis sent out from the hydrogen generator 1 is supplied to the combustor2; the ignition device 5 provided at the combustor 2; and the controller30.

With the above configuration, in a case where flame extinction hasoccurred at the combustor 2 during the generation of thehydrogen-containing gas in the start-up process, an ignition operationfollowing the flame extinction of the combustor 2 is performed throughcontrol by the controller 30, in which the ignition operation of theignition device 5 is performed with the first on-off valve 8A opened.

Thus, in the hydrogen generation apparatus 100 according to the presentembodiment which includes the hydrogen generator 1 configured to performa reforming reaction using evaporative water, pressure damage to thehydrogen generation apparatus 100 that is caused by a gas amountincrease due to water evaporation when flame extinction occurs at thecombustor 2 is reduced as compared to the conventional art.

Embodiment 2

Hereinafter, specific configuration examples and operational examples ofa hydrogen generation apparatus according to Embodiment 2 of the presentinvention will be described with reference to the accompanying drawings.

It should be noted that the specific description given below merelyindicates examples of the hydrogen generation apparatus's features thatare recited above at the beginning of Description of Embodiments. Forexample, in the description of specific examples below, the same termsas those used above to specify respective components of the hydrogengeneration apparatus may be used with corresponding reference signsadded thereto. In such a case, in the description below, each devicespecified by a term with a reference sign added thereto is merely anexample of a component that is specified by the same term in the abovedescription of the hydrogen generation apparatus.

Accordingly, the above-described features of the hydrogen generationapparatus are not limited by the specific description given below.

[Example of Configuration of Hydrogen Generation Apparatus]

FIG. 2 is a block diagram showing an example of the configuration of thehydrogen generation apparatus according to Embodiment 2 of the presentinvention.

In FIG. 2, the same components as those of the hydrogen generationapparatus 100 according to Embodiment 1 are denoted by the samereference signs as those used in Embodiment 1, and a detaileddescription of such components is omitted below.

As shown in FIG. 2, a hydrogen generation apparatus 110 according to thepresent embodiment is different from the hydrogen generation apparatus100 according to Embodiment 1 in that the hydrogen generation apparatus110 additionally includes an exhaust heat recovery mechanism, which isconfigured to perform heat exchange between an exhaust gas dischargedfrom the combustor 2 and a first heating medium (e.g., water in a liquidform or an antifreezing fluid) flowing through a first heating mediumpassage 201.

To be specific, the hydrogen generation apparatus 110 according to thepresent embodiment includes: the flue gas passage 10 through which theexhaust gas flows; the first heating medium passage 201 through whichthe first heating medium flows; and a first heat exchanger 11 configuredto perform heat exchange between the exhaust gas which is ahigh-temperature gas and the first heating medium which is alow-temperature medium. The first heating medium passage 201 is providedwith a first pump 200. The first pump 200 causes the first heatingmedium to flow through the first heating medium passage 201. The firstheating medium passage 201 is provided with a first heat accumulator202. Accordingly, the first heat accumulator 202 stores therein thefirst heating medium which flows through the first heating mediumpassage 201. It should be noted that the operation of the first pump 200is controlled by the controller 30.

The exhaust gas acts as a heating fluid at the first heat exchanger 11.The exhaust gas, which is discharged from the combustor 2, is guidedinto the flue gas passage 10, and the exhaust gas is cooled down byusing the first heat exchanger 11. The first heating medium acts as aheat receiving fluid at the first heat exchanger 11. The first heatingmedium is heated through the heat exchange at the first heat exchanger11, and the first heating medium of which the temperature has beenincreased due to passing through the first heat exchanger 11 enters thefirst heat accumulator 202 and is then stored therein.

According to the above configuration, the high-temperature exhaust gasdischarged to the outside of the hydrogen generation apparatus 110 iscooled down through the heat exchange, which is advantageous. Inaddition, the heat from the exhaust gas recovered through the heatexchange can be utilized, which is also advantageous.

[Example of Operations of Hydrogen Generation Apparatus]

In the hydrogen generation apparatus 110 according to the presentembodiment, the heat from the exhaust gas is recovered by the firstheating medium via the first heat exchanger 11 as a result of the firstpump 200 being operated in at least one of the following periods: aperiod over which the ignition operation of the ignition device 5 isperformed after flame extinction has occurred at the combustor 2 duringthe hydrogen-containing gas generation in the start-up process of thehydrogen generation apparatus 110; and a period over which the pressureincrease suppressing operation is performed in the flame extinctionabnormal stop process.

The combustion air supply device 4 operates during the periods of thestart-up process, the hydrogen supply step, and the stop process of thehydrogen generation apparatus 110. A heat recovery operation, which isperformed in each of these steps and in which the heat from the exhaustgas is recovered by the first heating medium via the first heatexchanger 11, is described below.

In the start-up process and the hydrogen supply operation of thehydrogen generation apparatus 110, the air-fuel mixture is combusted bythe combustor 2. At the time, the first pump 200 is operated, and thefirst heating medium flowing through the first heating medium passage201 recovers, via the first heat exchanger 11, heat from the exhaust gas(here, a flue gas produced due to the combustion of the air-fuelmixture) of which the temperature is high due to the combustion. In thismanner, the high-temperature exhaust gas that is discharged to theoutside of the hydrogen generation apparatus 110 is cooled down throughthe heat recovery via the heat exchanger 11.

The combustion of the air-fuel mixture in the combustor 2 is notperformed in the following periods: a period over which the ignitionoperation of the ignition device 5 is performed after flame extinctionhas occurred at the combustor 2 during the start-up process of thehydrogen generation apparatus 110; and a period over which the pressureincrease suppressing operation is performed in the flame extinctionabnormal stop process. In these periods, however, the combustor 2 andthe hydrogen generator 1 in a high-temperature state act as heat sourcesfor the exhaust gas. In particular, immediately after the flameextinction abnormal stop process of the hydrogen generation apparatus110 has started, the operation amount of the combustion air supplydevice 4 is increased and thereby the flow rate of the combustion air isincreased. Accordingly, a large amount of heat is taken out of thecombustor 2 and the hydrogen generator 1 by the exhaust gas (here,mainly the combustion air). For this reason, there is a tendency for thetemperature of the exhaust gas to increase. Therefore, the heat from theexhaust gas is recovered by the first heating medium via the first heatexchanger 11 as a result of the first pump 200 being operated in atleast one of the following periods: a period over which the ignitionoperation of the ignition device 5 is performed after flame extinctionhas occurred at the combustor 2; and a period over which the pressureincrease suppressing operation is performed in the flame extinctionabnormal stop process. In this manner, even when the combustion of theair-fuel mixture is not performed by the combustor 2, it is preferred toperform, during a period over which the combustion air supply device 4operates, the heat recovery operation in which the heat from the exhaustgas is recovered by the first heating medium via the first heatexchanger 11.

As described above, the hydrogen generation apparatus 110 according tothe present embodiment includes: the first heat exchanger 11 configuredto perform heat exchange between the exhaust gas discharged from thecombustor 2 and the first heating medium; the first heating mediumpassage 201 through which the first heating medium flows; the first pump200 for causing the first heating medium to flow through the firstheating medium passage 201; and the first heat accumulator 202configured to store therein the heat recovered by the first heatingmedium. The controller 30 performs the heat recovery operation, in whichthe heat from the exhaust gas is recovered by the first heating mediumvia the heat exchanger 11, by operating the first pump 200 in at leastone of the following periods: a period over which the ignition operationof the ignition device 5 is performed after flame extinction hasoccurred at the combustor 2; and a period over which the combustion airis supplied from the combustion air supply device 4 in the flameextinction abnormal stop process in a state where the combustion is notperformed by the combustor 2.

According to the above configuration, the exhaust gas is cooled downappropriately through the above-described heat exchange in at least oneof the following periods: a period over which the ignition operation ofthe ignition device 5 is performed after flame extinction has occurredat the combustor 2; and a period over which the combustion air issupplied from the combustion air supply device 4 in the flame extinctionabnormal stop process in a state where the combustion is not performedby the combustor 2. In addition, the heat from the exhaust gas isrecovered through the heat exchange.

Embodiment 3

FIG. 3 is a block diagram showing an example of the configuration of afuel cell system according to Embodiment 3 of the present invention.

In FIG. 3, the same components as those of the hydrogen generationapparatus 110 according to Embodiment 2 are denoted by the samereference signs as those used in Embodiment 2, and a detaileddescription of such components is omitted below.

As shown in FIG. 3, the fuel cell system according to the presentembodiment includes a fuel cell which is used as the hydrogenutilization apparatus 7, and also includes: a second gas passage 9through which the gas that is sent out from the hydrogen generator 1 issupplied to the combustor 2 through an anode gas passage 7A of the fuelcell 7; and a second gas on-off valve 9A configured to open/block thesecond gas passage 9.

In the fuel cell system according to the present embodiment, the supplyof a combustion fuel to the combustor 2 in the start-up process isperformed in a manner described below, for example.

A first supply example is a case where, similar to the hydrogengeneration apparatuses according to Embodiments 1 and 2, the firston-off valve 8A is opened and the second and third on-off valves 9A and9B are closed, and in such a state, the hydrogen-containing gas sent outfrom the hydrogen generator 1 is used as a combustion fuel for thecombustor 2. In this case, the raw fuel from the raw fuel supply device20 is, when passing through the hydrogen generator 1, transformed into ahydrogen-containing gas. The hydrogen-containing gas is supplied to thecombustor 2 through the first gas passage 8 in a manner to bypass thefuel cell.

A second supply example is a case where the first on-off valve 8A isclosed and the second and third on-off valves 9A and 9B are opened, andin such a state, an off fuel gas sent out from the fuel cell is used asa combustion fuel for the combustor 2. In this case, the raw fuel fromthe raw fuel supply device 20 is, when passing through the hydrogengenerator 1, transformed into a hydrogen-containing gas. Thehydrogen-containing gas passes through the anode gas passage 7A of thefuel cell, and an off fuel gas that is discharged from the anode gaspassage 7A is supplied to the combustor 2 through the second gas passage9.

According to the above configuration, a high-temperature exhaust gasdischarged to the outside of the hydrogen generation apparatus 110 iscooled down, which is advantageous.

[Example of Normal Operations of Fuel Cell System]

Hereinafter, an example of normal operations of the fuel cell system 200according to Embodiment 3 of the present invention is described. Itshould be noted that operations described below are performed as aresult of the controller 30 controlling respective components of thefuel cell system 200.

The normal operations of the fuel cell system 200 are roughlycategorized into the following steps: a start-up process, a powergeneration operation, a stop process, and a standby state. Since thesesteps are publicly known, they are described below briefly. It should benoted that the start-up process and the standby state are not describedbelow since the start-up process and the standby state are the same asthose of the hydrogen generation apparatus previously described inEmbodiment 1.

(Power Generation Operation)

When the temperature of the reforming catalyst layer of the hydrogengenerator 1 has been sufficiently increased so that ahydrogen-containing gas containing hydrogen at a high concentration canbe stably generated in the hydrogen generator 1 in the start-up process,the operation based on the first supply example is switched to theoperation based on the second supply example and the hydrogen-containinggas starts to be supplied to the fuel cell. The fuel cell generatespower by using the hydrogen-containing gas supplied from the hydrogengeneration apparatus 110 and an oxidizing gas (e.g., air) supplied froman oxidizing gas supply device (not shown).

(Stop Process)

The stop process of the fuel cell system is a step of stopping the fuelcell from generating power and stopping the hydrogen generationapparatus 110 from generating the hydrogen-containing gas.

The stop process is performed, for example, in the following case: acase where a user has inputted, via an operation device which is notshown, an instruction to stop the operation of the fuel cell system 200;or a case where the power demand of an electrical load has decreased tobe less than or equal to a predetermined power threshold, so that theelectrical load does not require power supply from the fuel cell.

In the stop process, the supply of the oxidizing gas from the oxidizinggas supply device (not shown) is stopped, and also, the same stopprocess as that described in Embodiment 1 is performed for the hydrogengeneration apparatus 110.

[Example of Operations Performed when Flame Extinction of Combustor hasOccurred during Hydrogen-Containing Gas Generation by HydrogenGeneration Apparatus in Start-Up Process]

In the fuel cell system 200 according to the present embodiment, ifflame extinction occurs at the combustor 2 during thehydrogen-containing gas generation by the hydrogen generation apparatus110 in the start-up process, then similar to the hydrogen generationapparatus according to Embodiment 1, the first on-off valve 8A is keptopened, and the supply of the raw fuel to the hydrogen generator 1 bymeans of the raw fuel supply device 20, the supply of water to thehydrogen generator 1 by means of the water supply device 12, and thesupply of the combustion air from the combustion air supply device 4 arecontinued, and the ignition operation of the ignition device 5 isperformed. Accordingly, in the fuel cell system 200 according to thepresent embodiment, similar to the hydrogen generation apparatus 100according to Embodiment 1, pressure damage to the hydrogen generationapparatus that is caused by a gas amount increase due to waterevaporation is reduced as compared to the conventional art at the timewhen the ignition operation is performed after flame extinction hasoccurred at the combustor.

Further, in the fuel cell system 200 according to the presentembodiment, similar to the hydrogen generation apparatus according toEmbodiment 2, the first heat exchanger 11 performs heat exchange betweenthe exhaust gas and the first heating medium (i.e., heat recovery fromthe exhaust gas) in at least one of the following periods: a period overwhich the ignition operation of the ignition device 5 is performed afterflame extinction has occurred at the combustor 2 during thehydrogen-containing gas generation by the hydrogen generation apparatus110 in the start-up process; and a period over which the pressureincrease suppressing operation is performed in the flame extinctionabnormal stop process.

Accordingly, in the fuel cell system according to the presentembodiment, similar to the hydrogen generation apparatus according toEmbodiment 2, heat recovery from the exhaust gas is performedappropriately through the above-described heat exchange in at least oneof the following periods: a period over which the ignition operation ofthe ignition device 5 is performed; and a period over which thecombustion air is supplied from the combustion air supply device 4 inthe flame extinction abnormal stop process in a state where thecombustion is not performed by the combustor 2. However, as analternative, the heat recovery operation of recovering heat from theexhaust gas may be avoided in at least one of the following periods: aperiod over which the ignition operation is performed; and a period overwhich the combustion air is supplied from the combustion air supplydevice 4 in the flame extinction abnormal stop process in a state wherethe combustion is not performed by the combustor 2.

[Variation 1]

The above-described fuel cell system according to Embodiment 3 isconfigured such that, while the hydrogen generation apparatus 110 isgenerating the hydrogen-containing gas in the start-up process, thehydrogen-containing gas that is sent out from the hydrogen generator 1is supplied to the combustor 2 according to the first supply example.However, a fuel cell system according to Variation 1 is configured suchthat, in the start-up process, the hydrogen-containing gas that is sentout from the hydrogen generator 1 is supplied to the combustor 2according to the second supply example.

In this case, in the start-up process, at the temperature increasingstep which is performed before the hydrogen generator 1 startsgenerating the hydrogen-containing gas, the gas that is sent out fromthe hydrogen generator 1 and that contains the raw fuel is supplied tothe combustor 2 through the first gas passage 8 according to the firstsupply example. After the hydrogen generator 1 starts generating thehydrogen-containing gas, the hydrogen-containing gas that is sent outfrom the hydrogen generator 1 is supplied to the combustor 2 accordingto the second supply example. Moreover, not limiting to theabove-described configurations, the fuel cell system may be configurednot including the first gas passage 8 and the first on-off valve 8A,such that the combustible gas is supplied to the combustor 2 through theanode gas passage 8A of the fuel cell according to the second supplyexample from the start of the temperature increasing step of thehydrogen generator 1. This configuration is particularly suitable for asolid oxide fuel cell of an internal reforming type which has a hydrogengeneration part internally.

In this variation, in a case where flame extinction has occurred at thecombustor 2 during the hydrogen-containing gas generation by thehydrogen generation apparatus in the start-up process, the ignitionoperation of the ignition device 5 is performed with the second on-offvalve 9A and the third on-off valve 9B kept opened. In this case,similar to the hydrogen generation apparatus according to Embodiment 1,the supply of the raw fuel to the hydrogen generator 1 by means of theraw fuel supply device 20, the supply of water to the hydrogen generator1 by means of the water supply device 12, and the supply of thecombustion air from the combustion air supply device 4 are continued. Asa result, in the fuel cell system according to Variation 1, similar tothe hydrogen generation apparatus according to Embodiment 1, pressuredamage to the hydrogen generation apparatus that is caused by a gasamount increase due to water evaporation is reduced as compared to theconventional art at the time when the ignition operation is performedafter flame extinction has occurred at the combustor. It should be notedthat in the fuel cell system according to Variation 1, the “secondon-off valve” is realized as the second on-off valve 9A and the thirdon-off valve 9B. However, not limiting to this, an alternativeconfiguration may be employed in which either one of the second on-offvalve 9A or the third on-off valve 9B is provided on the second gaspassage 9, and the second on-off valve 9A or the third on-off valve 9Bwhich is provided on the second gas passage 9 acts as the “second on-offvalve”.

The fuel cell system according to this variation may be configured suchthat, similar to the fuel cell system according to Embodiment 3, a heatrecovery operation of recovering heat from the exhaust gas is performedin at least one of the following periods: a period over which theignition operation of the ignition device 5 is performed after flameextinction has occurred at the combustor 2 during thehydrogen-containing gas generation by the hydrogen generation apparatus110 in the start-up process; and a period over which the pressureincrease suppressing operation is performed in the flame extinctionabnormal stop process. Alternatively, the fuel cell system according tothis variation may be configured such that the heat recovery operationis not performed.

[Variations of Hydrogen Generation Apparatuses According to Embodiments1 and 2, Fuel Cell System According to Embodiment 3, and Fuel CellSystem According to Variation 1]

In the hydrogen generation apparatuses 100 and 110 according toEmbodiments 1 and 2, the fuel cell system 200 according to Embodiment 3,and the fuel cell system according to Variation 1, the controller 30 isconfigured such that, if flame extinction occurs at the combustor 2during the hydrogen-containing gas generation by the hydrogen generationapparatus in the start-up process, then the controller 30 causes the rawfuel supply device 20 to supply the raw fuel to the hydrogen generator1, causes the water supply device 12 to supply water to the hydrogengenerator 1, causes the combustion air supply device 4 to supply thecombustion air to the combustor 2, and performs the ignition operationof the ignition device 5.

The above configuration provides the following advantage: if thecombustor 2 is re-ignited through the ignition operation of the ignitiondevice 5, then the generation of the hydrogen-containing gas by thehydrogen generation apparatus can be continued smoothly since the rawfuel has been supplied to the hydrogen generator 1 by means of the rawfuel supply device 20, water has been supplied to the hydrogen generator1, and the combustion air has been supplied to the combustor 2 by meansof the combustion air supply device 4.

In a hydrogen generation apparatus according to a variation describedbelow, the controller 30 is configured to stop at least one of thefollowing supplies when the ignition operation is performed after flameextinction has occurred at the combustor 2: the supply of the raw fuelto the hydrogen generator 1 by means of the raw fuel supply device 20;and the supply of water to the hydrogen generator 1 from the watersupply device 12. In a case where the raw fuel supply device 20 isconfigured as, for example, a booster pump, the controller 30 may stopthe booster pump from operating in order to stop supplying the raw fuelto the hydrogen generator 1. In a case where the water supply device 12is configured as, for example, a pump, the controller 30 may stop thepump from operating in order to stop supplying water to the hydrogengenerator 1.

Even if at least one of the supply of the raw fuel to the hydrogengenerator 1 by means of the raw fuel supply device 20 and the supply ofwater to the hydrogen generator 1 from the water supply device 12 isstopped, steam is still generated from water that remains within thehydrogen generator 1 due to residual heat from the hydrogen generator 1.This causes volume expansion of gas within the hydrogen generator 1. Thevolume expansion causes the combustible gas to be forced out of thehydrogen generator 1, and as a result, the combustible gas iscontinuously supplied to the combustor 2. Accordingly, it is expectedthat the combustor 2 can be ignited through the ignition operation ofthe ignition device 5.

Also in this variation, in a case where an ignition operation is to beperformed, the on-off valve configured to open/block the gas passagethrough which the gas sent out from the hydrogen generator 1 is suppliedto the combustor 2 is kept opened during a period after an occurrence offlame extinction at the combustor 2 until the ignition operation isperformed. Accordingly, also in this variation, it is expected thatpressure damage to the hydrogen generation apparatus 100 that is causedby gas volume expansion due to water evaporation is reduced as comparedto the conventional art at the time when the ignition operation isperformed after flame extinction has occurred at the combustor 2 duringthe generation of the hydrogen-containing gas in the start-up process.

[Other Variations of Hydrogen Generation Apparatus of Embodiment 2]

Hereinafter, a description is given of various variations of the exhaustheat recovery mechanism used in the hydrogen generation apparatus 110according to Embodiment 2. It should be noted that the variations of theexhaust heat recovery mechanism which are described below are applicableto the exhaust heat recovery mechanism of the fuel cell system 200according to Embodiment 3 and the exhaust heat recovery mechanism of thefuel cell system according to Variation 1 although such applications arenot shown and described below.

Each of FIG. 4, FIG. 5, and FIG. 6 is a block diagram showing avariation of the exhaust heat recovery mechanism used in the hydrogengeneration apparatus according to Embodiment 2.

It should be noted that components common among these diagrams aredenoted by reference signs that are common among the diagrams. In thedescription below, there are cases where a detailed description of theconfiguration of such common components is omitted.

FIG. 4 shows an exhaust heat recovery mechanism which is configured torecover, via a secondary cooling system, the heat from the exhaust gasdischarged from the combustor 2, and to store the recovered heat in asecond heat accumulator 212 of the secondary cooling system.

There is provided a second heat exchanger 213 configured to recover heatfrom the first heating medium flowing through the first heating mediumpassage 201, and the heat recovered from the first heating medium istransmitted to a second heating medium (e.g., water in a liquid form oran antifreezing fluid) flowing through a second heating medium passage211. That is, the first heating medium acts as a heating fluid at thesecond heat exchanger 213, and the second heating medium acts as a heatreceiving fluid at the second heat exchanger 213. When a second pump 210operates, the second heating medium flows through the second heatingmedium passage 211. As a result, the second heating medium of which thetemperature has been increased due to passing through the second heatexchanger 213 enters the second heat accumulator 212, and is then storedtherein.

In a hydrogen generation apparatus 120 shown in FIG. 4, the controller 3controls not only the first pump 200 but also the second pump 210 tooperate in at least one of the following periods: a period over whichthe ignition operation of the ignition device 5 is performed in a statewhere the combustion is not performed by the combustor 2; and a periodover which the combustion air is supplied from the combustion air supplydevice 4 in the flame extinction abnormal stop process in a state wherethe combustion is not performed by the combustor 2. Accordingly, theheat from the exhaust gas is eventually recovered by the second heatingmedium, and as a result, the heat from the exhaust gas is stored in thesecond heat accumulator 212.

FIG. 5 shows an exhaust heat recovery mechanism which is configured toperform a switching operation with a first switch 221 (e.g., a solenoidthree-way valve), such that the first heating medium flows into a firstbypass passage 222 when the first heating medium recovers the heat fromthe exhaust gas.

The first bypass passage 222 connects a passage, of the first heatingmedium passage 201, that is upstream from the first heat accumulator 202with a passage, of the first heating medium passage 201, that isdownstream from the first heat accumulator 202 in a manner to bypass thefirst heat accumulator 202. The first switch 221 is configured to switchthe destination of the first heating medium that has passed through thefirst heat exchanger 11, between the first heat accumulator 202 and thefirst bypass passage 222. The first bypass passage 222 is provided witha radiator 220 which is configured to radiate the heat from the firstheating medium that passes through the first bypass passage 222.

In a hydrogen generation apparatus 130 shown in FIG. 5, the controller30 controls the first pump 200 to operate and controls the first switch221 to switch the destination of the first heating medium to the firstbypass passage 222, in at least one of the following periods: a periodover which the ignition operation of the ignition device 5 is performedin a state where the combustion is not performed by the combustor 2; anda period over which the combustion air is supplied from the combustionair supply device 4 in the flame extinction abnormal stop process in astate where the combustion is not performed by the combustor 2.Accordingly, the heat recovered by the first heating medium is radiatedvia the radiator 220.

FIG. 6 shows an exhaust heat recovery mechanism which is configured torecover, via the secondary cooling system, the heat from the exhaust gasdischarged from the combustor 2, and to store the recovered heat in thesecond heat accumulator 212 of the secondary cooling system. Thesecondary cooling system includes a second bypass passage 232 whichconnects a passage, of the second heating medium passage 211, that isupstream from the second heat accumulator 212 with a passage, of thesecond heating medium passage 211, that is downstream from the secondheat accumulator 212 in a manner to bypass the second heat accumulator212. There is provided a second switch 231 configured to switch thedestination of the second heating medium that has passed through thesecond heat exchanger 213, between the second heat accumulator 212 andthe second bypass passage 232. The second bypass passage 232 is providedwith a radiator 230 which is configured to radiate the heat from thesecond heating medium that passes through the second bypass passage 232.

In a hydrogen generation apparatus 140 shown in FIG. 6, the controller30 controls the first pump 200 and the second pump 210 to operate andcontrols the second switch 231 to switch the destination of the secondheating medium to the second bypass passage 232, in at least one of thefollowing periods: a period over which the ignition operation of theignition device 5 is performed in a state where the combustion is notperformed by the combustor 2; and a period over which the combustion airis supplied from the combustion air supply device 4 in the flameextinction abnormal stop process in a state where the combustion is notperformed by the combustor 2. Accordingly, the heat recovered by thesecond heating medium is radiated via the radiator 230.

INDUSTRIAL APPLICABILITY

The present invention is directed to a hydrogen generation apparatusthat includes a hydrogen generator configured to perform a reformingreaction using evaporative water, and the present invention provides ahydrogen generation apparatus configured to reduce, as compared to theconventional art, pressure damage caused to the hydrogen generationapparatus when flame extinction has occurred at the combustor, and alsoprovides a fuel cell system including the hydrogen generation apparatus.The hydrogen generation apparatus and the fuel cell system including thehydrogen generation apparatus according to the present invention areuseful in various applications. For example, the hydrogen generationapparatus and the fuel cell system including the hydrogen generationapparatus are applicable to a household hydrogen utilization apparatus(e.g., a fuel cell) co-generation system.

REFERENCE SIGNS LIST

1 hydrogen generator

2 combustor

4 combustion air supply device

5 ignition device

7 hydrogen utilization apparatus

7A anode

7C cathode

8 first gas passage

8A first on-off valve

9 second gas passage

9A second on-off valve

9B third on-off valve

10 flue gas passage

11 first heat exchanger

12 water supply device

20 raw fuel supply device

21 detector

30 controller

100, 110, 120, 130, 140 hydrogen generation apparatus

200 fuel cell system

201 first heating medium passage

202 first heat accumulator

212 second heat accumulator

200 first pump

210 second pump

211 second heating medium passage

213 second heat exchanger

220, 230 radiator

222 first bypass passage

232 second bypass passage

1. A hydrogen generation apparatus comprising: a hydrogen generatorconfigured to generate a hydrogen-containing gas through a reformingreaction by using a raw fuel and steam; a combustor configured to heatthe hydrogen generator; an on-off valve configured to open/block a gaspassage through which the gas that is sent out from the hydrogengenerator is supplied to the combustor; an ignition device provided atthe combustor; a flame detector configured to detect presence or absenceof a flame of the combustor; and a controller, wherein the combustor isconfigured to perform combustion during generation of thehydrogen-containing gas in a start-up process by using the gas that issupplied to the combustor through the gas passage, and in a case wherethe flame detector has detected flame extinction of the combustor duringthe generation of the hydrogen-containing gas in the start-up process,the controller performs an ignition operation of the ignition devicewith the on-off valve kept opened.
 2. The hydrogen generation apparatusaccording to claim 1, comprising: a combustion air supply deviceconfigured to supply combustion air to the combustor; a raw fuel supplydevice configured to supply the raw fuel to the hydrogen generator; anda water supply device configured to supply water to the hydrogengenerator, wherein in the case where the flame detector has detected theflame extinction of the combustor during the generation of thehydrogen-containing gas in the start-up process, the controller causesthe raw fuel supply device and the water supply device to supply the rawfuel and the water to the hydrogen generator, and causes the combustionair supply device to supply the combustion air to the combustor, andperforms the ignition operation of the ignition device, with the on-offvalve kept opened.
 3. The hydrogen generation apparatus according toclaim 1, wherein if the combustor is not successfully ignited throughthe ignition operation, the controller performs a stop process of thehydrogen generation apparatus.
 4. The hydrogen generation apparatusaccording to claim 2, wherein if the combustor is not successfullyignited through the ignition operation, the controller controls anoperation amount of the combustion air supply device such that theoperation amount becomes greater than when the hydrogen-containing gasis being generated in the start-up process.
 5. The hydrogen generationapparatus according to claim 1, comprising: a first gas passage throughwhich the gas that is sent out from the hydrogen generation apparatus isguided into the combustor in a manner to bypass a hydrogen utilizationapparatus which uses the hydrogen-containing gas; and a first on-offvalve configured to open/block the first gas passage, wherein thecombustor is configured to combust, during the generation of thehydrogen-containing gas in the start-up process, the gas that issupplied to the combustor through the first gas passage, and in the casewhere the flame detector has detected the flame extinction of thecombustor during the generation of the hydrogen-containing gas in thestart-up process, the controller performs the ignition operation of theignition device with the first on-off valve kept opened.
 6. The hydrogengeneration apparatus according to claim 1, comprising: a heat exchangerconfigured to perform heat exchange between an exhaust gas dischargedfrom the combustor and a heating medium; a heating medium passagethrough which the heating medium flows; a pump configured to cause theheating medium to flow through the heating medium passage; and a heataccumulator configured to store heat that has been recovered by theheating medium, wherein the controller causes the pump to operate duringthe ignition operation of the ignition device.
 7. The hydrogengeneration apparatus according to claim 1, wherein a period over whichthe ignition operation is performed in said case is shorter than aperiod over which the ignition operation is performed at the start ofthe combustion of the combustor in the start-up process.
 8. A fuel cellsystem comprising the hydrogen generation apparatus according to claim 1and a fuel cell configured to generate power by using thehydrogen-containing gas that is supplied to the fuel cell from thehydrogen generation apparatus.
 9. A fuel cell system comprising: asecond gas passage through which a gas that is sent out from thehydrogen generation apparatus according to claim 1 is guided into thecombustor through a fuel cell; and a second on-off valve configured toopen/block the second gas passage, wherein the combustor is configuredto combust, during the generation of the hydrogen-containing gas in thestart-up process, the gas that is supplied to the combustor through thesecond gas passage, and in the case where the flame detector hasdetected the flame extinction of the combustor during the generation ofthe hydrogen-containing gas in the start-up process, the controllerperforms the ignition operation of the ignition device with the secondon-off valve kept opened.